Process of making abrasive disks



A. J. DOERMANN PROCESS 4OF MAKING ABRASIVE DISKS Re. y18,872

June 2o, 1933.

Original Filed Aug. 12, i927 f6 lthe abra Reissued June 20, 193,3'4 y fUNITED STAT as PATENT OFFICE.

ALBBT J.. DQERMANN, OF CHICAGO, ILLINOIS.

PROCESS 0F MAKING ABRASIVE DISKS Original No. 1,785,437, datedDecember'l, 1930, Serial No. 212,550, led August 12, 17927. Applicationfor reissue led lecember 14,

This invention relates to improvements in the process of making abrasivedisks, and more es ecially such disks composed of powdered a rasive andcement. For example,

sive ma consist of ground or powdered carborundyilm, emer dint or anysimilar suitable substanceandybe bound together by any suitable cementsuch as, for example, heat-hardenable resin.

l Heretofore in manufacturing abrasive any relatively .ilar to Fig. 2showing a method of smooth, hard surface disks of 'this type diflicultyhas been encountered in obtainlng a firm union between the particles ofabrasive and the cement. By the use of my invention I produce a diskwith a uniformly agglomerated mixture without hard or soft spots in thefinished material.

Another feature of my invention is the provision of means for fasteningabacking on the disk.

Other features and advantages of my invention will a pear more fully asI proceed with my speci cation.

In the drawing accompanying this'application Figure 1 is a view in`perspective of a mold showing a disk cast or molded therein, Fig..2.isva vertical sectional view of the device shown in Fig. 1, Fig. 3 is aview similar to Fig. 2 showing a method of applying the backing to thedisk, Fig. 4 is a view simroducthe disk a :re atively for the purpose ofapplying a backing thereto, Fig. 4 is a view showin the met od ofapplying the backing to the sk of Fig. 4, Fig. 5 is a view similar ingon the back .of

to Fig. 4* showing another methodof applyt ing a backing tothe disk.

n the practice of my invention, I take suitable proportions of abrasiveand cement. For example, I may use ten pounds of abrasive to fromsixteen to twenty-six ounces of heat-hardenable resin. The resin is ireferably finely powdered before being meted.

In the practice of my invention I first take the proper amount ofpowdered abrasive and treat the same with a suitable hard drying oil,for exam le, Chinawood or tung oi coating the a rasive grains inthis-manner assists in causing the cement to adhere' to 19'32. SerialNo. 647,229.

After the grains of abrasive have thus I beenv coated with hard dryingoil to the proper extent, the proper amount of Vpowdered heat hardenableresin with other cement is added and the same thoroughly mixed.

I have found that the use of a hard drying oil such as a Chinawood ortung oily isv far superior to coatings such as `creosote which hasheretofore beenremployed.

After the coating of the abrasive with the oil and the addition of theheat-hardenable resin and the mixing, the mixture is ready to i beplaced in a form for formin' the disk. This is shown in Figs. 1 and 2, wdicates the mold and abrasive and'cement. After the mixture is spreadevenly in the mold the saine may be ironed in with an ordinaryplasterers trowel and then struck oil' with an .ordinary slicing bar andis then ready for the oven. 1`

, The material is then placed in an oven and baked at a propertemperature, in the usual manner, for a sulcient length of time, as iswell known in the art, preferably wlthout the use of any pressure.

I shall now describe the different methods for placing' a backing on thedisk. Such a backing, it is to be understood, may be made either ofcloth, paper, metal, or any other suitable material `and may be either aplain sheet, perforated, or woven metal, de end ing upon the use forwhich thedisk 1s inended.

ere 10 ine In Fig. 3 I have shown a method of placmg on the disk abacking at the same time 'that the disk is molded. As here shown, theSbacking must -be some non-combustible ma" terial, for example wovenasbestos fabric. A .sheet of this material as indicated by 12 is rstplaced in the mold 10 and then a thin layer 13 of powdered resin dustedon. The mixture of abrasive and cement as indicated by-11 is *then lacedon top. The whole is then baked in t ing causes the to the disk.

e usual manner and the bakbacking 12 to adhere firmly In the methodshown in Figs. 4 and 4*, there is first placed in the mold 10 a layer 14of very fine abrasive mixed with resin. mixture of abrasive and cementis then placed on'top. The whole is then baked.

When the disk is removed from the mold' be baked again to make thebacking adhere.

In such case, of course, the backing 15 must be some non-combustiblematerial.

In Fig. 5 I have shown another method of fastening a backing to the disk11. In the practice of this method, the. disk is formed as shown inFigs. 1 and 2. One surface of the disk is then coated with any hardcement, air drying filler, such cement as indicated by 1-7. This gives avery smooth surface to one side of the disk. On top of this smoothsurface there is then applied a5 layer 18 of cement which may be, forexample, any air cate of soda or a mixture of magnesium oxide andmagnesium chloride. The backing 19 vis then placed on and held on thedis by means of the layer of cement 18. If desired, the layer of cement18 may be a heathardenable resin cement which requires baking, and ifsuch, of course, the backing 19 must be some noncombustible material.

Another advantage in the use of China- Wood or tung oil over'creosote isthat the for- V^consisting of wet grains of abrasive to cause the sameto mer gives off no obnoxious fumes,`and also dries harder thancreosote.

WhileI have yshown Iand described certain embodiments of m invention, itis t0 be understood that it is capable of many modifications. Changes,therefore, in the construction and arrangement maybe made withoutdeparting from the spirit and scope of the invention disclosed in theappended claims, in which it is my intention to claim all novelty in myinvention as'broadly as possible in view of the prior art.

I claim: l

1. The process of making an abrasive disk comprising, mixing powderedabrasive and heat-hardenable cement, placing the same in a mold with alayer of finely powdered abrasiveon the bottom, and ma ing the same.

2. The process of making an abrasive disk treating powdered abrasivewith Chinawood. oil to wet ythe grains., mixas, for example, iron dryingcement such as silibecome coated withgrains of cement adhering to thewet surface of the grains of abrasive and baking the mixture.

3. An abrasive disk comprising a. main body of relatively'coarse ibonded with heat-hardenable cement, and a face or surface of relativelyfinely powdered abrasive.

4. An abrasive disk comprising abrasive granules and a. heat-hardenedresin bond, one surface of said disk being coated with finely powderedabrasive and -being relatively impermeable.

5. A bonded abrasive" article comprising abrasive granules'coated withhardened drying oil and bonded with a heat-hardened resin.

abrasive granules coated with l a hardened Chinawood oil and bonded witha heat-hardened resin.

7 A composite abrasive article comprising an abrasive body adapted forgrinding on one of' its plane surfaces and a backing attached to thesurface which is opposite the lgrinding face by a cement, said abrasivebody consisting of a permeable abrading portion of abrasive particlesbonded with a heat-hardened resin and a substantially impermeablesurface layer vadjacent to the backing, said surface layer being capableof preventing a material penetration of the )by the cement.

8. A composite abrasive article comprising V an abrasive body adaptedfor grinding on one of its plane surfaces and a backing cemented to thesurface which is opposite the grinding face, said abrasive bodyconsisting of a permeable abrading portion of abrasive particles bondedwith a heat-hardened resin and a substantially impermeable surface layeradjacent to the backing.

In testimony whereof, I aix my signature.

ALBERT J. DOERMANN.

abrasive granules 6. A bonded abrasive-article 4comprisingl main portionof the body ing powdered Bakelite resiny cement with the y

